[PATCH v3] readline: backport a patch to fix for caller setting rl_prompt to NULL

["João Henrique Ferreira de Freitas" <joaohf@gmail.com>]

I've observed this issue affecting iwctl and connmanctl.

Patching readline solves the issue.

The original patch from [5] mixes many fixes in one commit. I've extract
only what matters to solve the issues observed with connman and iwd. The
final patch is the same patch sent by readline author to readline's mail list [6].

References:

1: https://gitlab.archlinux.org/archlinux/packaging/packages/readline/-/issues/1
2: https://gitlab.archlinux.org/archlinux/packaging/packages/readline/-/commit/b30636dc66fc783a091af51b049dc5240f861dd0
3: https://lists.gnu.org/archive/html/bug-readline/2025-07/msg00007.html
4: https://lore.kernel.org/connman/20251018212411.181909-1-jsbronder@cold-front.org/
5: https://cgit.git.savannah.gnu.org/cgit/readline.git/commit/display.c?h=devel&id=488d7edc22894d30b6de7f2d4190bf7403f63ffd
6: https://lists.gnu.org/archive/html/bug-readline/2025-07/txtmA7rksnmmi.txt

Fixes [YOCTO #16047]

CC: Jose Quaresma <quaresma.jose@gmail.com>
CC: Khem Raj <raj.khem@gmail.com>
CC  Paul Barker <paul@pbarker.dev>
Signed-off-by: João Henrique Ferreira de Freitas <joaohf@gmail.com>
---

Notes:
    changes in v3:
    - remove unnecessary whitespace change
    - keep notes for readline patch

 ...for-caller-setting-rl_prompt-to-NULL.patch | 40 +++++++++++++++++++
 meta/recipes-core/readline/readline_8.3.bb    |  1 +
 2 files changed, 41 insertions(+)
 create mode 100644 meta/recipes-core/readline/readline/fix-for-caller-setting-rl_prompt-to-NULL.patch

diff --git a/meta/recipes-core/readline/readline/fix-for-caller-setting-rl_prompt-to-NULL.patch b/meta/recipes-core/readline/readline/fix-for-caller-setting-rl_prompt-to-NULL.patch
new file mode 100644
index 0000000000..a23e2f3bce
--- /dev/null
+++ b/meta/recipes-core/readline/readline/fix-for-caller-setting-rl_prompt-to-NULL.patch
@@ -0,0 +1,40 @@
+From a0a4c011c0c5e598c5b51cbf81d3b4501fa72e0c Mon Sep 17 00:00:00 2001
+From: Chet Ramey <chet.ramey@case.edu>
+Date: Thu, 30 Oct 2025 14:19:41 -0300
+Subject: [PATCH] fix for caller setting rl_prompt to NULL
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+The original patch came from [1, 2] and it has been integrated into
+readline git repository, commit (488d7edc22894d30b6de7f2d4190bf7403f63ffd)
+
+This patch has only the fix needed to solve the follow issues [3,4].
+
+I added the original author as this patch has been sent through readline mail
+list.
+    
+1: https://lists.gnu.org/archive/html/bug-readline/2025-07/msg00007.html
+2: https://lists.gnu.org/archive/html/bug-readline/2025-07/txtmA7rksnmmi.txt
+3: https://lore.kernel.org/connman/20251018212411.181909-1-jsbronder@cold-front.org/
+4: https://gitlab.archlinux.org/archlinux/packaging/packages/readline/-/issues/1
+
+Upstream-Status: Backport [https://cgit.git.savannah.gnu.org/cgit/readline.git/commit/display.c?h=devel&id=488d7edc22894d30b6de7f2d4190bf7403f63ffd]
+Signed-off-by: João Henrique Ferreira de Freitas <joaohf@gmail.com>
+---
+ display.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/display.c b/display.c
+index 9aa8c7b..edb525d 100644
+--- a/display.c
++++ b/display.c
+@@ -783,7 +783,7 @@ _rl_optimize_redisplay (void)
+ 
+ /* Useful shorthand used by rl_redisplay, update_line, rl_move_cursor_relative */
+ #define INVIS_FIRST()	(local_prompt_invis_chars[0])
+-#define WRAP_OFFSET(line, offset)  ((line <= prompt_last_screen_line) ? local_prompt_invis_chars[line] : 0)
++#define WRAP_OFFSET(line, offset)  ((line <= prompt_last_screen_line && local_prompt_invis_chars) ? local_prompt_invis_chars[line] : 0)
+ 
+ #define W_OFFSET(line, offset) ((line) == 0 ? offset : 0)
+ #define VIS_LLEN(l)	((l) > _rl_vis_botlin ? 0 : (vis_lbreaks[l+1] - vis_lbreaks[l]))
diff --git a/meta/recipes-core/readline/readline_8.3.bb b/meta/recipes-core/readline/readline_8.3.bb
index a2f23eb353..b425b78e1f 100644
--- a/meta/recipes-core/readline/readline_8.3.bb
+++ b/meta/recipes-core/readline/readline_8.3.bb
@@ -2,6 +2,7 @@ require readline.inc
 
 SRC_URI += "file://norpath.patch \
             file://fix-for-readline-event-hook.patch \
+            file://fix-for-caller-setting-rl_prompt-to-NULL.patch \
             "
 
 SRC_URI[archive.sha256sum] = "fe5383204467828cd495ee8d1d3c037a7eba1389c22bc6a041f627976f9061cc"